ABSTRACT
L-tagatose was produced directly from L-psicose by subjecting the same biomass suspension to microbial reduction followed by oxidation using a newly isolated bacteria Enterobacter aerogenes 230S. After various optimizations, it was observed that cells grown on xylitol have the best conversion potential. Moreover, E. aerogenes 230S converted L-psicose to L-tagatose at a faster rate in the presence of polyols such as glycerol, D-sorbitol, ribitol, L-arabitol, D-mannitol and xylitol. At 5% substrate concentration, the conversion ratio of L-psicose to L-tagatose was above 60% in the presence of glycerol. Identity of crystalline L-tagatose was confirmed by HPLC analysis, (13)C-NMR spectra, and optical rotation.
Subject(s)
Enterobacter aerogenes/metabolism , Fructose/metabolism , Hexoses/metabolism , Sugar Alcohols/metabolism , Biotechnology/methods , Carbohydrates/chemistry , Carbon/chemistry , Chromatography, High Pressure Liquid , Hydrogen-Ion Concentration , Magnetic Resonance Spectroscopy , Models, Chemical , Oxygen/chemistryABSTRACT
The crystalline form of 1-de-oxy-l-mannitol, C(6)H(14)O(5), exists as an extensively hydrogen-bonded structure with each mol-ecule acting as a donor and acceptor for five hydrogen bonds. There are no unusual crystal-packing features; the absolute configuration was determined from the use of 6-de-oxy-l-mannose (l-rhamnose) as the starting material.
ABSTRACT
X-ray crystallography showed that the title compound, C(6)H(12)O(5), crystallizes in the α-pyran-ose form with the six-membered ring in a chair conformation. The crystal structure exists as a three-dimensional hydrogen-bonded network of mol-ecules with each mol-ecule acting as a donor and aceptor for four hydrogen bonds. The absolute configuration was determined by the use of l-fucose as starting material.
ABSTRACT
D-psicose, a new alternative sweetener, was produced from allitol by microbial oxidation of the newly isolated strain Enterobacter aerogenes IK7. Cells grown in tryptic soy broth medium (TSB) supplemented with D-mannitol at 37 degrees C were found to have the best oxidation potential. The cells, owing to broad substrate specificity, oxidized various polyols (tetritol, pentitol, and hexitol) to corresponding rare ketoses. By a resting cell reaction, 10% of allitol was completely transformed to the product D-psicose, which thus becomes economically feasible for the mass production of D-psicose. Finally, the product was crystallized and confirmed to be D-psicose by analytical methods.
